Forwards coach Tony Windo insisted poor execution had cost Worcester Warriors as they suffered a 17-5 defeat to local rivals Gloucester Rugby in the LV= Cup.
Wing Chris Pennell raced over for a well worked team try in the second half, but Worcester suffered a second defeat in the pool stages to deal a body blow to any semi-final qualification hopes.
And Windo believed a lack of cohesion on the day was also down to enforced time off for many of the Sixways squad.
"We looked ring rusty at times and our execution wasn't as good as we would expect," said Windo, after returning to a club where he was idolised during his playing days.
"We didn't hold onto the ball for long enough, we didn't have the opportunity to build up phases and when we did try to kick for field position our kicking game wasn't as good as we wanted it to be.
"We took the opportunity over the last few weeks to rest a lot of players because it's such a physical domestic competition we are in. The same players can't do it every week.
"It's a difficult situation to be in. We had to do what we did and rest players to keep them fresh for a big end to the season in the Guinness Premiership.
"We have had a lot of young players involved in the Amlin Challenge Cup and they stepped up and played exceptionally well.
"However, the three week layoff left some of the players ring rusty. But we will be going full out next week and we must now use it as a stepping stone to go back into the Guinness Premiership on the front foot."
Back row Chris Cracknell had an eventful debut for Warriors as he was yellow carded in the second half for not rolling away near the try line as Worcester looked to keep Gloucester out.
However, Windo believed the recent signing had done well on his first outing and the fact the Warriors did not concede when down to 14 men was a positive to take from the cup tie.
"It will be interesting to see the yellow card again," said Windo. "I felt it was quite harsh and Chris felt he was contesting the ball. It is where it was on the field that didn't do him any favours.
"I would say, apart from that, Chris fronted up very well and when we went down to 14 men the boys defended exceptionally well. To go through the ten minutes without conceding a point is one of the very few positives.
"We wanted to progress in this competition, but we were also aware that these two cup games are preparation for going back into Guinness Premiership rugby," added Windo.
"We have good professionals and they know we haven't performed as we could and they are bitterly disappointed. If any man goes to work and lets himself down he is disappointed - that is where we are today."
Niall Annett and Phil Dowson are among three changes to the Warriors starting line-up for their trip to Franklin's Gardens to take on Northampton Saints in the Aviva Premiership this Saturday (kick-off 3pm).